On what's been said about the role of oxygen in lees stirring (and of
course I'm talking post fermentation):

I wouldn't say lees stirring is done to oxygenate wine, but I wouldn't
say it's really done for the purposes of absorbing oxygen either -
that's just a useful extra.

Stirring inadvertently adds oxygen to a wine when the barrel/vessel is
opened and the turbulence associated with lees stirring occurs. Whilst
the aim isn't to add oxygen to the wine at stirring, I would say it is
necessary this takes place in the reductive environment created by the
stirring itself.

Ben